James Anthony Williams will be charged Tuesday with the first-degree murder of a 31-year-old Sierra Club worker outside her condominium on New Year’s Eve, the King County Prosecuting Attorney’s Office announced Saturday.

Authorities said Williams, 48, said he stabbed Shannon Harps.

Williams has a history of violence and has been diagnosed with paranoid schizophrenia.

But Senior Deputy Prosecutor Scott O’Toole said his office has concluded “he is competent” to stand trial for the death of Harps, based on Williams’ interviews with authorities and his demeanor.

Authorities also linked Williams to Harps’ death through DNA and said he was in the Capitol Hill area near the slaying. Police reported that Williams agreed to give detectives a DNA sample that night.

A source familiar with the investigation said DNA evidence came from a knife and from beneath Harps’ fingernails. Midday Friday, the state crime laboratory told Seattle police that Williams’ DNA matched.

Williams has been in King County Jail since Jan. 16 for skipping a required appointment with a mental-health provider.

Williams has a history of mental illness dating to his teenage years in Arkansas, according to court records.

His criminal record includes convictions for burglary and felony theft in Arizona, drug use in Texas, assault and battery in Oklahoma and three aggravated-assault convictions in Florida.

In 1995, Williams was arrested in Seattle after shooting a man at a bus stop on Second Avenue and Union Street, according to court documents. He was convicted of assault, sentenced to prison and released last year.

Williams and his sister were raised by their mother’s relatives after she died, according to his aunt, Marilyn Walker, of Camden, Ark.

Court documents indicate that while Williams worked short stints as a painter, wallboard hanger and oil-field worker, he was typically unemployed and sometimes homeless.

Harps, an Ohio native, moved to Seattle about three years ago to work as an organizer for the Northwest Region of the Sierra Club.

At 7:15 p.m. New Year’s Eve, she was fatally stabbed outside her East Howell Street building while returning home with groceries. Authorities believe the attack was random.

Tan Vinh: 206-515-5656 or tvinh@seattletimes.com; on Twitter: @tanvinhseattle. Tan Vinh is a features writer for the Seattle Times. He hikes and drinks for a living, though he never does both at the same time. At least not while on the clock.